Most contemporary computers, including personal computers as well as more powerful workstations, have some graphics processing capability. This capability is often provided by one or more special purpose processors in addition to the central processing unit (CPU). Graphics processing is a task that requires a relatively large amount of data. Accordingly, GPUs typically have their own graphics memories (also referred to as video memories or video random access memory (VRAM)). All computer systems are limited in the amount of data they can process in a given amount of time. One of the limiting factors of performance is availability of memory. In particular the availability of cache memory affects system performance.
FIG. 1 is a block diagram of various elements of a prior art computer system 100. System 100 includes an operating system (OS) 104 that executes on a CPU. The OS 104 has access to memory including a disk 106. The amount of memory 106 that is allocated for cache is small in absolute terms compared to the amount of graphics memory 108 available on GPU 102. In addition, graphics direct memory access (DMA) is approximately 20-100 times faster than access to disk 106. However, OS 104 does not have direct access to GPU memory 108, even if the GPU 102 is not performing graphics processing.
Currently when systems that have GPUs and GPU memories are not performing graphics processing, the GPU memory is essentially unused (approximately 90% of VRAM is unused during non-graphics work). It would be desirable to provide a system in which the CPU could access the memory resources of the GPU to increase system performance.